Fukushima Tracers in Global RTOFS (Text)

NCEP/NWS deployed particle tracing to predict the movement of radionuclides
in the ocean shortly after the Japanese nuclear disaster near Fukushima.

The full three-dimensional tracer computations
capability of HYCOM has also been implemented to predict the dispersion of
radionuclides in a nested North-West Pacific sub-region model within
Global RTOFS. The boundary conditions of the nested sub-region are updated
daily from the nowcast fields of the global model. These tracer forecasts
have been implemented at NCEP Central Operations.

IMPORTANT NOTE:
These results only track initial releases of radionuclides from the
Fukushima Dai'Ichi Nuclear Power Plant over the time period of 12 March 2011
through 26 April 2011. No subsequent discharges from the facility are
considered in this simulation.

To view the tracer images:

Select a View: (SSH is Sea Surface Height, Cs-137 is Cesium-137)

Pick the From and To dates

Press Start

The dates are selectable from April 27, 2011
to the near present.

Changing the view or the dates will reload the viewer.
Note, selecting a long date range can result in a very slow
browser or even a browser crash. We recommend limiting the loops to about a
month or two at a time.

The Cesium-137 radioactivity is given in units of Bequerels (Bq),
One Bq is defined as the
activity of a quantity of radioactive material in which one nucleus decays
per second.

Simulation of Cs-137 through RTOFS_EP_WPA, after the
Fukushima-Daichii nuclear accident.

A numerical simulation for the time evolution of the 3-dimensional Cs-137
concentration after the Fukushima-Daichii nuclear plant accident was
performed, and is referred as RTOFS_EP_WPA (RTOFSEpisodic Tracer for
the Western Pacific).

The simulation uses the HYCOM model, in the domain 134°E-30°W,
15°N-60°N, at
1/12° horizontal resolution, with 32 vertical layers, nested to the
daily nowcast archives of the
Global RTOFS model,
a global operational ocean
prediction model at EMC, in strong partnership with the Navy). The
regional simulation is run in forecast mode (with no data assimilation
inside the domain). The HYCOM source is version 2.2.36tr, with
atmospheric deposition of tracers.

Cs-137 is added as an atmospheric deposition to the top layer of the
ocean model, with the horizontal and time evolution provided by NOAA's
HYSPLIT-NSC (V.3) for Cs-137, based on Cs-137 source by Japan's Nuclear
Safety Commission's. HYSPLIT-NSC covers the whole period of deposition,
March 12-April 21, 2011, with a total deposition of 5.4 PBq over the
ocean (1 PBq=1015 Becquerels).

At model day April 26 2011, the direct ocean discharge of Cs-137 from
waters released from the plant was added as simulated by NOS' ROMS
coastal model (Lanerole, Patchen, et al, 2012 Ocean Sciences meeting,
Salt Lake City), normalized to 4.5 PB of total direct discharge.

The 3-D Cs-137 concentration is followed in a simulation to estimate the
importance of patches in the Pacific Ocean.